Synthesis and photovoltaic properties of 4,9-dithien-2′-yl-2,1,3-naphthothiadiazole-based D-A copolymers

A series of donor-acceptor (D-A) conjugated copolymers (PBDTNT, PCDTNT, PFDTNT, and PNDTNT) based on a new acceptor unit of 4,9-dithien-2′-yl-2,1,3-naphthothiadiazole (DTNT) and different donor unit of benzodithiophene, carbazole, fluorene, or naphthalene, were synthesized and characterized as donor in polymer solar cells (PSCs). The effect of different donor units on the physicochemical properties of the polymers was investigated systematically. The PSCs based on PBDTNT/PC70BM gave a PCE of 2.73%, with a high Voc of 0.90 V.322